Sometimes these are discussed as being compulsory, or are stated as being so in the introductory booklet you have to read before registering for the retreat, and other times a more relaxed approach is taken and they appear to be merely suggested courses of action. There is a strong onus on the individual to take responsibility for themselves on the retreat, which might account for this.

Deposit all valuables, passports, mobile phones, watches, money (except for a small amount to buy supplies from the on-site shop) and anything else you want to keep safe with reception at registration.

Phones are a distraction, watches are not needed due to the system of bells and alarms can be a disturbance to others in breaking silence.